scholarly journals Unveiling the bovine embryo transcriptome during the maternal-to-embryonic transition

Reproduction ◽  
2009 ◽  
Vol 137 (2) ◽  
pp. 245-257 ◽  
Author(s):  
Christian Vigneault ◽  
Catherine Gravel ◽  
Maud Vallée ◽  
Serge McGraw ◽  
Marc-André Sirard
Keyword(s):  
Cdna Library ◽  
Developmental Stages ◽  
Protein Biosynthesis ◽  
Subtractive Hybridization ◽  
Culture Conditions ◽  
Bovine Embryo ◽  
Maternal Mrna ◽  
Activation Of Transcription ◽  
Early Embryos ◽  
Genome Activation

Bovine early embryos are transcriptionally inactive and subsist through the initial developmental stages by the consumption of the maternal supplies provided by the oocyte until its own genome activation. In bovine, the activation of transcription occurs during the 8- to 16-cell stages and is associated with a phase called the maternal-to-embryonic transition (MET) where maternal mRNA are replaced by embryonic ones. Although the importance of the MET is well accepted, since its inhibition blocks embryonic development, very little is known about the transcripts expressed at this crucial step in embryogenesis. In this study, we generated and characterized a cDNA library enriched in embryonic transcripts expressed at the MET in bovine. Suppression subtractive hybridization followed by microarray hybridization was used to isolate more than 300 different transcripts overexpressed in untreated late eight-cell embryos compared with those treated with the transcriptional inhibitor, α-amanitin. Validation by quantitative RT-PCR of 15 genes from this library revealed that they had remarkable consistency with the microarray data. The transcripts isolated in this cDNA library have an interesting composition in terms of molecular functions; the majority is involved in gene transcription, RNA processing, or protein biosynthesis, and some are potentially involved in the maintenance of pluripotency observed in embryos. This collection of genes associated with the MET is a novel and potent tool that will be helpful in the understanding of particular events such as the reprogramming of somatic cells by nuclear transfer or for the improvement of embryonic culture conditions.

scholarly journals Exploring the function of long non-coding RNA in the development of bovine early embryos

2015 ◽  
Vol 27 (1) ◽  
pp. 40 ◽  
Author(s):  
Julieta Caballero ◽  
Isabelle Gilbert ◽  
Eric Fournier ◽  
Dominic Gagné ◽  
Sara Scantland ◽  
...  
Keyword(s):  
Cumulus Cells ◽  
Culture Conditions ◽  
Translation Control ◽  
Functional Characterisation ◽  
Non Coding Rna ◽  
Activation Of Transcription ◽  
Embryonic Genome ◽  
Early Embryos ◽  
Developmental Rates ◽  
Genome Activation

Now recognised as part of the cellular transcriptome, the function of long non-coding (lnc) RNA remains unclear. Previously, we found that some lncRNA molecules in bovine embryos are highly responsive to culture conditions. In view of a recent demonstration that lncRNA may play a role in regulating important functions, such as maintenance of pluripotency, modification of epigenetic marks and activation of transcription, we sought evidence of its involvement in embryogenesis. Among the numerous catalogued lncRNA molecules found in oocytes and early embryos of cattle, three candidates chosen for further characterisation were found unexpectedly in the cytoplasmic compartment rather than in the nucleus. Transcriptomic survey of subcellular fractions found these candidates also associated with polyribosomes and one of them spanning transzonal projections between cumulus cells and the oocyte. Knocking down this transcript in matured oocytes increased developmental rates, leading to larger blastocysts. Transcriptome and methylome analyses of these blastocysts showed concordant data for a subset of four genes, including at least one known to be important for blastocyst survival. Functional characterisation of the roles played by lncRNA in supporting early development remains elusive. Our results suggest that some lncRNAs play a role in translation control of target mRNA. This would be important for managing the maternal reserves within which is embedded the embryonic program, especially before embryonic genome activation.

scholarly journals Different co-culture systems have the same impact on bovine embryo transcriptome

Reproduction ◽  
2017 ◽  
Vol 154 (5) ◽  
pp. 695-710 ◽  
Author(s):  
A Vitorino Carvalho ◽  
E Canon ◽  
L Jouneau ◽  
C Archilla ◽  
L Laffont ◽  
...  
Keyword(s):  
Early Development ◽  
Embryo Development ◽  
Developmental Stages ◽  
Developmental Rate ◽  
Cell Types ◽  
Culture Conditions ◽  
Bovine Embryo ◽  
Culture Systems ◽  
Beneficial Impact ◽  
Reduce Cell Survival

During the last few years, several co-culture systems using either BOEC or VERO feeder cells have been developed to improve bovine embryo development and these systems give better results at high oxygen concentration (20%). In parallel, the SOF medium, used at 5% O2, has been developed to mimic the oviduct fluid. Since 2010s, the SOF medium has become popular in improving bovine embryo development and authors have started to associate this medium to co-culture systems. Nevertheless, little is known about the putative benefit of this association on early development. To address this question, we have compared embryo transcriptomes in four different culture conditions: SOF with BOEC or VERO at 20% O2, and SOF without feeders at 5% or 20% O2. Embryos have been analyzed at 16-cell and blastocyst stages. Co-culture systems did not improve the developmental rate when compared to 5% O2. Direct comparison of the two co-culture systems failed to highlight major differences in embryo transcriptome at both developmental stages. Both feeder cell types appear to regulate the same cytokines and growth factors pathways, and thus to influence embryo physiology in the same way. In blastocysts, when compared to culture in SOF at 5% O2, BOEC or VERO seems to reduce cell survival and differentiation by, at least, negatively regulating STAT3 and STAT5 pathways. Collectively, in SOF medium both blastocysts rate and embryo transcriptome suggest no influence of feeder origin on bovine early development and no beneficial impact of co-culture systems when compared to 5% O2.

scholarly journals Quantitative analysis of RNA abondance for CTCF during reprogramming of bovine embryo from oocyte to blastocyst

2015 ◽  
Vol 58 (1) ◽  
pp. 171-175
Author(s):  
M. Amiri Roudbar ◽  
H. Dehghani ◽  
M. Tahmoorespur ◽  
A. Zahmatkesh ◽  
H. Adeldust ◽  
...  
Keyword(s):  
Transcriptional Repression ◽  
Developmental Stages ◽  
Mature Oocyte ◽  
Preimplantation Embryos ◽  
Bovine Embryo ◽  
Immature Oocytes ◽  
Embryonic Genome ◽  
Maternal Effect Gene ◽  
Regulatory Functions ◽  
Genome Activation

Abstract. CTCF is a highly conserved protein among eukaryotes and it is involved in many of regulatory functions including, transcriptional repression and activation, chromatin insulation, imprinting, X chromosome inactivation, higher-order chromatin organization, and alternative splicing. Studies performed on mouse embryos indicate that CTCF can be a maternal-effect gene, and is essential for normal development of embryos. CTCF can be used as a molecular effector for the proper epigenetic establishment of embryonic development. The aim of this study was to determine changes in transcript levels of the CTCF gene in bovine preimplantation embryos. RNA was extracted from immature and mature oocytes and embryos at various developmental stages (two-cell, four-cell, eight-cell, and blastocysts). Results showed that the amounts of CTCF transcripts decreased in mature oocyte in comparison with immature oocytes, but this change was not significant. In addition, the amount of CTCF transcript in embryos at two-cell, four-cell, eight-cell, and blastocyst stages significantly increased in comparison with immature oocytes. These data show that CTCF expression in bovine embryo begins at minor embryonic genome activation.

scholarly journals 2 The landscape of accessible chromatin in bovine oocytes and early embryos

2020 ◽  
Vol 32 (2) ◽  
pp. 125
Author(s):  
H. Ming ◽  
J. Sun ◽  
R. Pasquariello ◽  
J. R. Herrick ◽  
Y. Yuan ◽  
...  
Keyword(s):  
Regulatory Networks ◽  
Bovine Embryo ◽  
Embryonic Genome Activation ◽  
Genome Wide ◽  
Embryonic Genome ◽  
Early Embryos ◽  
Germinal Vesicles ◽  
Genome Activation ◽  
Bovine Oocytes ◽  
Accessible Chromatin

Chromatin reorganization governs gene expression regulation during pre-implantation development. However, the global chromatin landscape and its dynamics in this period remain unexplored in bovine. In this study, we constructed a genome-wide map of accessible chromatin in bovine oocytes and early embryos using an improved assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq). We analysed pools of 20 germinal vesicles or MII oocytes or 2-, 4-, 8-, 16-cell, morula, and blastocyst stage invitro-produced embryos. We conducted ATAC-seq on six pools for each stage and an additional four pools of invivo-derived morula and blastocysts and six replicates using individual Day 14 elongating embryos. We obtained ~110 million paired end reads uniquely mapped to the bovine reference genome for each stage. Hierarchical clustering, t-distributed stochastic neighbour embedding, and principal component analysis showed four distinct patterns for open chromatin status: (1) low accessibility in germinal vesicles and MII oocytes and in 2- and 4-cell embryos; (2) significantly elevated accessibility in 8-cell, 16-cell, and morula embryos; (3) less accessibility in blastocysts; and (4) extremely high accessibility in elongating embryos. This dynamic and sequential chromatin remodelling is consistent with transcription activation during the bovine minor embryonic genome activation from fertilization to 4-cell, major embryonic genome activation at 8-cell, first differentiation at blastocyst and drastic transcription initiation for embryo elongation. Genome-wide characteristics of accessible chromatin showed (1) accessible chromatin near the transcription start sites of active genes and CpG-rich promoters; (2) widespread accessible chromatin regions extensively overlapped with transposable elements; (3) distal peaks preferentially enriched for repeats including LINE, SINE, and LTR from 8-cell to morula embryos, especially for LTR, whereas enrichment in simple repeats were found from oocytes to 4-cell and in elongating embryos; and (4) highly stage-specific transcription factor motifs in distal peaks were unveiled. By integrating the maps of chromatin accessibility with bovine embryo transcriptomes and DNA methylomes, we found promoter accessibility and DNA methylation in bovine embryos correlated with both gene activities and CpG densities. Most importantly, we constructed the regulatory networks of stage-specific expressed genes and stage-specific activated genes with three omics datasets in bovine early embryos and revealed conserved and distinctive transcriptional regulatory networks between invivo- and invitro-derived embryos. This comprehensive analysis revealed critical features of the chromatin landscape and epigenetic reprogramming during bovine early embryo development.

The Fate of Mitochondria in Ibex-hirus Reconstructed Early Embryos

2004 ◽  
Vol 36 (5) ◽  
pp. 371-374 ◽  
Author(s):  
Yan Jiang ◽  
Shu-Zhen Liu ◽  
Yan-Ling Zhang ◽  
Man-Xi Jiang ◽  
Qing-Yuan Sun ◽  
...  
Keyword(s):  
Endangered Species ◽  
Single Cell ◽  
Nuclear Transfer ◽  
Developmental Stages ◽  
Culture Conditions ◽  
Capra Ibex ◽  
Reconstructed Embryos ◽  
Early Embryos ◽  
Donor Cells

Abstract Inter-species nuclear transfer could be used to preserve North Goat (Capra ibex), an endangered species. We established the culture conditions for ibex-hirus reconstructed embryos and optimized the method for DNA extractions of a single cell and early cloned embryo. By using mitochondria-specific probes of ibex and hirus respectively we found that mitochondria of donor cells can co-exist with recipients in 1-cell and 2-cell stages of the reconstructed embryos but not in the following developmental stages.

scholarly journals Argonaute 2 is a key regulator of maternal mRNA degradation in mouse early embryos

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Jia-Ming Zhang ◽  
Wei-Bo Hou ◽  
Jia-Wei Du ◽  
Ming Zong ◽  
Kai-Lun Zheng ◽  
...  
Keyword(s):  
Small Interfering Rnas ◽  
Control Of Gene Expression ◽  
Argonaute 2 ◽  
Developmental States ◽  
Maternal Mrna ◽  
Early Embryos ◽  
Rna Activation ◽  
Cell Embryo ◽  
Maternal Mrnas ◽  
Genome Activation

AbstractIn mammalian early embryos, the transition from maternal to embryonic control of gene expression requires timely degradation of a subset of maternal mRNAs (MRD). Recently, zygotic genome activation (ZGA)-dependent MRD has been characterized in mouse 2-cell embryo. However, in early embryos, the dynamics of MRD is still poorly understood, and the maternal factor-mediated MRD before and along with ZGA has not been investigated. Argonaute 2 (Ago2) is highly expressed in mouse oocyte and early embryos. In this study, we showed that Ago2-dependent degradation involving RNA interference (RNAi) and RNA activation (RNAa) pathways contributes to the decay of over half of the maternal mRNAs in mouse early embryos. We demonstrated that AGO2 guided by endogenous small interfering RNAs (endosiRNAs), generated from double-stranded RNAs (dsRNAs) formed by maternal mRNAs with their complementary long noncoding RNAs (CMR-lncRNAs), could target maternal mRNAs and cooperate with P-bodies to promote MRD. In addition, we also showed that AGO2 may interact with small activating RNAs (saRNAs) to activate Yap1 and Tead4, triggering ZGA-dependent MRD. Thus, Ago2-dependent degradation is required for timely elimination of subgroups of maternal mRNAs and facilitates the transition between developmental states.

scholarly journals Single cell RNA-seq reveals genes vital to in vitro fertilized embryos and parthenotes in pigs

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zhi-Qiang Du ◽  
Hao Liang ◽  
Xiao-Man Liu ◽  
Yun-Hua Liu ◽  
Chonglong Wang ◽  
...  
Keyword(s):  
Embryo Development ◽  
Gene Networks ◽  
Regulatory Networks ◽  
Rna Binding ◽  
Expression Patterns ◽  
Early Embryo ◽  
Specific Factor ◽  
Early Embryos ◽  
Genome Activation

AbstractSuccessful early embryo development requires the correct reprogramming and configuration of gene networks by the timely and faithful execution of zygotic genome activation (ZGA). However, the regulatory principle of molecular elements and circuits fundamental to embryo development remains largely obscure. Here, we profiled the transcriptomes of single zygotes and blastomeres, obtained from in vitro fertilized (IVF) or parthenogenetically activated (PA) porcine early embryos (1- to 8-cell), focusing on the gene expression dynamics and regulatory networks associated with maternal-to-zygote transition (MZT) (mainly maternal RNA clearance and ZGA). We found that minor and major ZGAs occur at 1-cell and 4-cell stages for both IVF and PA embryos, respectively. Maternal RNAs gradually decay from 1- to 8-cell embryos. Top abundantly expressed genes (CDV3, PCNA, CDR1, YWHAE, DNMT1, IGF2BP3, ARMC1, BTG4, UHRF2 and gametocyte-specific factor 1-like) in both IVF and PA early embryos identified are of vital roles for embryo development. Differentially expressed genes within IVF groups are different from that within PA groups, indicating bi-parental and maternal-only embryos have specific sets of mRNAs distinctly decayed and activated. Pathways enriched from DEGs showed that RNA associated pathways (RNA binding, processing, transport and degradation) could be important. Moreover, mitochondrial RNAs are found to be actively transcribed, showing dynamic expression patterns, and for DNA/H3K4 methylation and transcription factors as well. Taken together, our findings provide an important resource to investigate further the epigenetic and genome regulation of MZT events in early embryos of pigs.

scholarly journals Retinoic acid signaling is critical during the totipotency window in early mammalian development

2021 ◽  
Author(s):  
Ane Iturbide ◽  
Mayra L. Ruiz Tejeda Segura ◽  
Camille Noll ◽  
Kenji Schorpp ◽  
Ina Rothenaigner ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Regulatory Networks ◽  
Es Cells ◽  
Embryonic Stem ◽  
Mammalian Development ◽  
Cell Stage ◽  
Cell Potential ◽  
Cellular Models ◽  
Early Embryos ◽  
Genome Activation

AbstractTotipotent cells hold enormous potential for regenerative medicine. Thus, the development of cellular models recapitulating totipotent-like features is of paramount importance. Cells resembling the totipotent cells of early embryos arise spontaneously in mouse embryonic stem (ES) cell cultures. Such ‘2-cell-like-cells’ (2CLCs) recapitulate 2-cell-stage features and display expanded cell potential. Here, we used 2CLCs to perform a small-molecule screen to identify new pathways regulating the 2-cell-stage program. We identified retinoids as robust inducers of 2CLCs and the retinoic acid (RA)-signaling pathway as a key component of the regulatory circuitry of totipotent cells in embryos. Using single-cell RNA-seq, we reveal the transcriptional dynamics of 2CLC reprogramming and show that ES cells undergo distinct cellular trajectories in response to RA. Importantly, endogenous RA activity in early embryos is essential for zygotic genome activation and developmental progression. Overall, our data shed light on the gene regulatory networks controlling cellular plasticity and the totipotency program.

Characterization of isolated bovine preantral follicles based on morphology, diameter and cell number

Zygote ◽  
2020 ◽  
Vol 28 (2) ◽  
pp. 154-159
Author(s):  
Juliana I. Candelaria ◽  
Anna C. Denicol
Keyword(s):  
Granulosa Cells ◽  
Developmental Stages ◽  
Assisted Reproductive Technologies ◽  
Reproductive Technologies ◽  
Cell Number ◽  
Culture Conditions ◽  
Preantral Follicles ◽  
Secondary Stage

SummaryPreantral follicles are a potential reservoir of oocytes to be used in assisted reproductive technologies. With the increasing interest in developing techniques to grow preantral follicles in vitro, and as the bovine emerges as an appropriate model species to understand human folliculogenesis, the establishment of an accurate classification of developmental stages is needed. Classification of bovine preantral follicles has been mostly based on histological analysis and estimation models, which may not translate well to correctly characterize preantral follicles isolated from the ovary. In this study, we classified bovine preantral follicles by morphology upon isolation, determined diameter and number of granulosa cells by direct counting, and compared our results with previous studies reporting bovine preantral follicle classification. Follicles were isolated via homogenization of ovary tissue and classified into primary, early secondary and secondary stage based on morphology and number of layers of granulosa cells. Diameter was individually measured and Hoechst 33342 was used as a nuclear stain to count granulosa cells. We found that follicles classified by morphology into primary, early secondary, and secondary had different mean diameter and cell number (P < 0.01); cell number and diameter were positively correlated, as were cell density and cell number in each developmental stage (P < 0.01). Results obtained here were mostly in agreement with previous classifications based on histological sections and on isolated follicles, with some discrepancies. The present data add accuracy to classification of bovine preantral follicles that is critical to optimize culture conditions to produce developmentally competent oocytes.

Expression of the HSP 70.1 gene, a landmark of early zygotic activity in the mouse embryo, is restricted to the first burst of transcription

Development ◽  
1995 ◽  
Vol 121 (1) ◽  
pp. 113-122 ◽  
Author(s):  
E. Christians ◽  
E. Campion ◽  
E.M. Thompson ◽  
J.P. Renard
Keyword(s):  
Dna Replication ◽  
Mouse Embryo ◽  
Culture Conditions ◽  
Hsp 70 ◽  
Cell Stage ◽  
Embryonic Genome ◽  
Genome Activation ◽  
Alpha Amanitin ◽  
Zygotic Genome

Activation of the mouse embryonic genome at the 2-cell stage is characterized by the synthesis of several alpha-amanitin-sensitive polypeptides, some of which belong to the multigenic hsp 70 family. In the present work we show that a member of this family, the HSP 70.1 gene, is highly transcribed at the onset of zygotic genome activation. Transcription of this gene began as early as the 1-cell stage. Expression of the gene continued through the early 2-cell stage but was repressed before the completion of the second round of DNA replication. During this period we observed that the level of transcription was modulated by in vitro culture conditions. The coincidence of repression of HSP70.1 transcription with the second round of DNA replication was not found for other transcription-dependent polypeptides synthesized at the 2-cell stage.

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